1. Field of the Invention
The present invention relates to a fuel injection apparatus which increases a pressure of fuel within a fuel tank by a fuel pump, and injects to supply the fuel having the increased pressure to an engine via a fuel injection valve, and more particularly to a fuel distribution pipe to which the fuel having the increased pressure is supplied and a plurality of fuel injection valves are attached.
2. Description of Conventional Art
The conventional fuel distribution pipe to which a plurality of fuel injection valves are attached is shown in FIGS. 8, 9 and 10.
FIG. 8 is a plan view of the lower side of the fuel distribution pipe, FIG. 9 is a cross sectional view along a line Lxe2x80x94L in FIG. 8, and FIG. 10 is a cross sectional view showing a state in which the fuel injection valves are attached in a line Mxe2x80x94M and the fuel distribution pipe is fixed and arranged to a fixing portion.
The present conventional art relates to a fuel distribution pipe for a 4-cylinder engine which is provided with four fuel injection valves and has four fuel distribution pipes to which the respective fuel injection valves are attached.
In FIGS. 8 and 9, first to fourth fuel distribution pipes are arranged from the left to the right.
A first fuel distribution pipe 20 is structured such that an injection valve insertion hole 20A is opened upward in FIG. 9, a fuel introduction hole 20B is horizontally provided leftward from the right end, and the left end of the fuel introduction hole 20B is communicated with the injection valve insertion hole 20A.
Further, reference symbol 20C denotes a mounting hole. The mounting hole 20C is provided in parallel to the longitudinal axial line of the injection valve insertion hole 20A, and is formed in one side of the injection valve insertion hole 20A. (The mounting hole 20C is shown in FIG. 8.)
In this case, in the first fuel distribution pipe 20, a hole 20D open to the left end is not communicated with the injection valve insertion hole 20A.
A second fuel distribution pipe 21 is structured such that an injection valve insertion hole 21A is opened upward, a first fuel introduction hole 21B is horizontally provided leftward from the right end, a second fuel introduction hole 21C is horizontally provided rightward from the left end, and the first and second fuel introduction holes 21B and 21C are both communicated with the injection valve insertion hole 21A.
Further, reference symbol 21D denotes a mounting hole. The mounting hole 21D is provided in the same direction as that of the injection valve insertion hole 21A, and is formed in one side of the injection valve insertion hole 21A.
The third fuel distribution pipe is the same as the second fuel distribution pipe, however, a description will be given by using new reference symbol for making the description easy.
A third fuel distribution pipe 22 is structured such that an injection valve insertion hole 22A is opened upward, a first fuel introduction hole 22B is horizontally provided leftward from the right end, a second fuel introduction hole 22C is horizontally provided rightward from the left end, and the first and second fuel introduction holes 22B and 22C are both communicated with the injection valve insertion hole 22A.
Further, reference symbol 22D denotes a mounting hole. The mounting hole 22D is provided in the same direction as that of the injection valve insertion hole 22A, and is formed in one side of the injection valve insertion hole 22A.
A fourth fuel distribution pipe 23 is structured such that an injection valve insertion hole 23A is opened upward, a fuel introduction hole 23B is horizontally provided rightward from the left end, and the right end of the fuel introduction hole 23B is communicated with the injection valve insertion hole 23A. Further, reference symbol 23C denotes a mounting hole. The mounting hole 23C is provided in parallel to the longitudinal axial line of the injection valve insertion hole 23A, and is formed in one side of the injection valve insertion hole 23A.
In this case, in the fourth fuel distribution pipe 23, a hole 23D open to the right end is not communicated with the injection valve insertion hole 23A.
In accordance with the fuel distribution pipe mentioned above, the fuel introduction hole 20B of the first fuel distribution pipe 20 and the second fuel introduction hole 21C of the second fuel distribution pipe 21 are arranged so as to be opposed to each other, and they are connected by a first fuel joint 24 constituted by a straight pipe.
Further, the first fuel introduction hole 21B of the second fuel distribution pipe 21 and the second fuel introduction hole 22C of the third fuel distribution pipe 22 are arranged so as to be opposed to each other, and they are connected by a second fuel joint 25 constituted by a T-shaped pipe.
Further, the first fuel introduction hole 22B of the third fuel distribution pipe 22 and the fuel introduction hole 23B of the fourth fuel distribution pipe 23 are arranged so as to be opposed to each other, and they are connected by a third fuel joint 26 constituted by a straight pipe.
Further, a rear end portion of a fuel injection valve J (shown in FIG. 10) is inserted and arranged within each of the injection valve insertion holes 20A, 21A, 22A and 23A of the respective fuel distribution pipes 20, 21, 22 and 23, and a leading end portion of each of the fuel injection valves J is inserted and arranged within a guide hole 26B of a throttle body 26 in which an intake passage 26A is provided.
Then, in such a state, the respective fuel distribution pipes 20, 21, 22 and 23 are fixed to the throttle body 26 corresponding to a fixing portion by inserting a screw member 27 within the mounting holes 20C, 21D, 22D and 23C, and screwing the screw member 27 with the throttle body 26.
In the manner mentioned above, each of the fuel distribution pipes 20, 21, 22 and 23 is fixed to the throttle body 26, and fuel is supplied to each of the fuel distribution pipes in the following manner.
A part of the fuel supplied to the second fuel joint 25 is introduced to the first fuel introduction hole 21B of the second fuel distribution pipe 21, and this fuel is supplied toward the fuel injection valve J attached to the injection valve insertion hole 21A of the second fuel distribution pipe 21.
Further, the fuel within the first fuel introduction hole 21B of the second fuel distribution pipe 21 is introduced to the fuel introduction hole 20B of the first fuel distribution pipe 20 via the second fuel introduction hole 21C and the first fuel joint 24, and this fuel is supplied toward the fuel injection valve J screwed with the injection valve insertion hole 20A of the first fuel distribution pipe 20.
On the other hand, another part of the fuel supplied to the second fuel joint 25 is introduced to the second fuel introduction hole 22C of the third fuel distribution pipe 22, and this fuel is supplied toward the fuel injection valve J attached to the injection valve insertion hole 22A of the third fuel distribution pipe 22.
Further, the fuel within the second fuel introduction hole 22C of the third fuel distribution pipe 22 is introduced to the fuel introduction hole 23B of the fourth fuel distribution pipe 23 via the first fuel introduction hole 22A and the third fuel joint 26, and this fuel is supplied toward the fuel injection valve J screwed with the injection valve insertion hole 23A of the fourth fuel distribution pipe 23.
In accordance with the fuel distribution pipe in the conventional fuel injection apparatus mentioned above, three fuel distribution pipes are required. That is, there are provided the first fuel distribution pipe 20, the second fuel distribution pipe 21 and the fourth fuel distribution pipe 23.
The first fuel distribution pipe 20 and the fourth fuel distribution pipe 23 can not be for common use, since the openings of the fuel introduction holes are provided at reverse positions. On the other hand, the second fuel distribution pipe 21 and the third fuel distribution pipe 22 can be for common use.
In accordance with the structure mentioned above, the number of the parts is increased. Accordingly, particularly in the case that the fuel distribution pipe is formed by a synthetic resin material, the number of the metal molds and the number of the cores are increased, so that it is impossible to reduce a manufacturing cost.
Further, three pipes comprising the first fuel joint 24, the second fuel joint 25 and the third fuel joint 26 are required as the pipes for connecting the respective fuel distribution pipes to form a flow path, and an O-ring for inhibiting the fuel from leaking from the fuel introduction hole is required in the outer periphery of each of the fuel joints, so that the number of the parts and the number of man-hour for assembling are increased, and this structure is not preferable.
Particularly, in the O-ring portion arranged in the outer periphery of the fuel joint, it is necessary to carry out an air tightness test so as to check the fuel leakage, whereby an increase of the number of man-hour for test is caused.
A fuel distribution pipe in a fuel injection apparatus in accordance with the present invention is made by taking the problems mentioned above into consideration, and an object of the present invention is to provide a fuel distribution pipe having a plurality of fuel injection valves attached thereto, in which the number of parts in the fuel distribution pipe and a fuel joint and the number of man-hour for assembling them are reduced, whereby an inexpensive fuel distribution pipe is provided.
In accordance with the present invention, in order to achieve the object mentioned above, there is provided a fuel distribution pipe in a fuel injection apparatus, in which fuel having a pressure increased by a fuel pump is supplied to a fuel distribution passage and a plurality of fuel injection valves for injecting and supplying the fuel within the fuel distribution passage toward an engine are provided, wherein the fuel distribution pipe comprises:
a fuel distribution passage formed along the longitudinal direction with one end being opened by a fuel introduction hole and another end being closed;
a plurality of injection valve insertion holes positioned apart from the longitudinal axial line Axe2x80x94A of the fuel distribution passage toward one side by a predetermined amount, having the longitudinal axial lines Dxe2x80x94D of the injection valve insertion holes crossing orthogonally to the longitudinal axial line Axe2x80x94A, having a leading end open toward one side B and a rear end communicated with the fuel distribution passage, and formed along the longitudinal axial line Axe2x80x94A with an interval E;
a plurality of mounting bosses formed orthogonally to a cross section including the longitudinal axial lines Dxe2x80x94D of the injection valve insertion holes and the longitudinal axial line Axe2x80x94A of the fuel distribution passage, and each having an upper end surface and a lower end surface being formed so as to uniformly protrude upward and downward on the basis of the longitudinal axial line Axe2x80x94A of the fuel distribution passage; and
mounting holes provided from the upper end surfaces of the respective mounting bosses toward the lower end surface, and provided apart from the longitudinal axial line of the fuel distribution passage toward one side B by a predetermined amount,
wherein fuel introduction holes of the fuel distribution pipe are arranged so as to oppose to each other, the longitudinal axial lines of the respective fuel distribution pipes are concentrically arranged, the respective fuel injection valve insertion holes are arranged so as to open toward the same direction, the opposing fuel introduction holes are connected by a single fuel joint, rear end portions of the fuel injection valves are arranged so as to be inserted to the respective fuel injection valve insertion holes, and the fuel distribution pipe is screwed with and fixed to fixing portions by screw members inserted to the respective mounting holes.
In accordance with the fuel distribution pipe of the present invention, since the respective fuel introduction holes of two fuel distribution pipes are arranged so as to oppose to each other, it is possible to arrange a plurality of injection valve insertion holes formed in the respective fuel distribution pipes in the same direction and at the same position, whereby it is possible to attach the rear ends of a plurality of fuel injection valves in the same direction and at the same position.
Further, since the mounting holes formed in the respective fuel distribution pipes can be also arranged in the same direction and at the same position, it is possible to make the positions of the fixing portions corresponding to the mounting holes common.
Further, the fuel introduction pipe for supplying the fuel to the fuel distribution pipe and the connection pipe for communicating the fuel introduction holes of the respective fuel distribution pipes can be achieved by a single fuel joint.